Need to Know About Radio Waves

Electromagnetic waves are radiated by accelerating charged particles. Radio waves have the longest wavelengths among electromagnetic waves. The frequency of radio waves is 300 GHz and less. 

Electromagnetic waves were discovered by the Scottish mathematician and physicist James Clerk Maxwell. His mathematical theory, now famously called Maxwell’s equation, predicted the existence of electromagnetic waves by recognizing the coupled electric and magnetic fields that could travel through space. 

We will learn all about what radio waves are, how they are used around us, etc., here.

Generation of Radio Waves

• Maxwell’s theory of electromagnetic waves was first proven by the German physicist Heinrich Hertz when he produced radio waves in his laboratory. 
• After that, Guglielmo Marconi invented the first radio transmitter and receiver around 1985. Radio communication began to be used significantly in the 1900s.
• Radio waves are naturally generated through radio noise made by lightning and other natural phenomena occurring in the atmosphere of Earth. 
• Moreover, all heated objects can produce high-frequency radio waves, such as a microwave.

Properties of Radio waves

Speed

We know radio waves are electromagnetic radiation. Hence, they can travel in a vacuum with the speed of light. On the other hand, the waves are slowed down in other mediums according to their permeability and permittivity. 

Wavelength

• The wavelength of any wave is the distance between the peaks of adjacent crests or troughs. 
• The wavelength is inversely proportional to the frequency of the wave. 
• the equation of wavelength and frequency can be

λ＝c/f and f = c/λ

where c is the distance travelled by radio waves in a vacuum. 

• A radio wave with a frequency of 1 MHz will have a wavelength of 299.79 m.

Polarisation 

Radio waves are electromagnetic waves, so they have the property of polarisation. 

• Polarisation is the process of restricting a wave’s oscillating electric field in one direction perpendicular to the direction of motion. Polarised radio waves are of three types:
  • Horizontally polarised radio wave: In this type of radio wave, the oscillation of the electric field is in a horizontal direction.
  • Vertically polarised radio wave: Here, the radio wave has an electric field oscillating vertically.
  • Circularly polarised radio wave: In a circularly polarised radio wave, the electric field rotates at a regular rate perpendicular to the direction of the wave. These waves are further divided into two types:
    • Right circularly polarised: the electric field rotates clockwise around the wave.
    • Left circularly polarised: the electric field around the wave rotates in an anti-clockwise direction.

• Antennas are used to emit polarised radio waves.     

Structure of radio waves

The structure of radio waves is given below:

Uses of Radio Waves

Radio waves are very significant in our lives. Some of these uses are:

Broadcasting

• One of the most significant uses of radio waves is in broadcasting. The prime technique used for this application is through the acceleration and deceleration of charges through conducting wires.
•  The range of signals in radio broadcasting usually ranges from 500 kHz to 1710 kHz (AM) or 88 MHz to 108 MHz (FM).
• For television broadcasting, the signals range from 55 MHz to 890 MHz.

Cellular networks

The communication industry uses the penetrating property of radio waves to establish cellular links. This is because radio waves are not hindered by any obstacles like trees, buildings, etc.

RADAR

• RADAR is the short form of ‘Radio Detection And Ranging’. 
• This system is used to detect the presence of any obstacle using radio waves. 
• Devices that utilise this system work by sending radio waves into the atmosphere. When these waves hit an obstacle, they bounce back. In this manner, the position of the obstacle can be determined.

Astronomy

Radio waves are used to view celestial bodies better as these waves are not affected by adverse weather conditions.

Radio Telemetry

• Telemetry is the collection of data from remote locations that are then transmitted back to monitoring equipment. 
• For example, radio waves are used to detect the exact position of wild animals tagged with the necessary equipment, such as trackers, to help track their movements.

Remote-Controlled Items

• Remote-controlled items such as remote control toys rely on the use of radio waves. 
• A receiver placed in the toy receives signals transmitted by the transmitter present in the controller. This enables people to operate the toy from a distance.

Submarines

Submarines use extremely low-frequency radio waves to establish a communication system with other submarines.

Medical Resonance Imaging (MRI)

Medical Resonance Imaging or MRI scans use radio waves to create a three-dimensional view of the patients’ organs.

Radio Sources

• Objects that emit radio waves are called radio sources. 
• Some of the things that generate radio waves are:
  • Hot, ionised interstellar gases generate radio waves. Celestial bodies and stars are some of the astronomical sources of radio waves. 
  • A natural source of radio waves is lightning. 

Conclusion

We have learned what radio waves are in this lesson. These waves are a type of electromagnetic wave that has the longest wavelengths. Heinrich Heinz l first discovered the method of generating them. 

Radio waves are of the frequency of 300 Hz and lower. One of their most important properties is their ability to be polarised. Radio waves play a significant role in establishing communication systems. We use several technologies in our day-to-day lives that use radio waves, such as remote-controlled objects, broadcasting, RADAR, radio astronomy, etc.